A capped trigonal prismatic cadmium complex with tetra‐ and tridentate ligands: bis­(tri­ethanol­amine)‐κ3N,O,O′;κ4N,O,O′,O′′‐cadmium(II) squarate monohydrate

In the crystal structure of the title compound, Cd(C₆H₁₅NO₃)₂](C₄O₄)·H₂O, a supramolecular structure is observed. The asymmetric unit consists of one unit of the cationic Cd complex, one water mol­ecule and two half‐squarate anions, each sitting on a crystallographic inversion center. The different coordinations of the two triethanolamine (TEA) ligands results in an unusual example of coordination number seven for the Cd^II ion. Both TEA ligands coordinate to the Cd^II ion, forming a distorted monocapped trigonal prismatic geometry with approximate C_2v symmetry. One of the TEA ligands acts as an N,O,O′‐tridentate ligand, whereas the other behaves as an N,O,O′,O′′‐tetradentate donor. The anions and cations are linked to one another by hydrogen bonds between hydroxy H atoms of the TEA ligands and squarate O atoms. The crystal structure is stabilized by O—H⋯O hydrogen bonds between the unligated water mol­ecule and a squarate O atom, together with a weak π–ring interaction between the ethyl­ene group of a TEA ligand and a squarate anion.